The present invention relates to a pickup arm device.
In a prior art pickup device, one end of an arm is securely attached to a rotary mount while the other end is connected with coupling means such as a lock nut to a head shell which is fabricated separately from the arm. A weight shaft is extended from the rotary mount in the direction opposite to that of the arm and carries a balance weight which may be displaced in the axial direction of the supporting shaft in either direction. The rotary mount is mounted with pivot bearings to a rotary shaft in such a way that the mount may nod up and down. The rotary shaft in turn is mounted on a base in such a way that the shaft may rotate about a vertical axis. Thus the pickup arm may nod up and down and rotate in a horizontal plane.
With the pickup arm device of the type described, there has been some attempt to reduce the weight of the arm main body and the head shell in order to improve the reproduction characteristcs. However, since the head shell and the coupling means for connecting the head shell to the arm main body are located at the free end of the arm main body, reduction in effective mass of the whole pickup arm device to a satisfactory degree cannot be attained. Thus the satisfactory improvements of reproduction characteristics cannot be obtained. Furthermore because of the coupling means which must be specially designed and fabricated, the pickup arm device becomes expensive.
In order to overcome the above problems, it has been proposed to form a head shell integral with an arm main body or to attach the head shell to the arm main body with set screws and to attach the other end of the arm main body to a rotary mount with coupling means such as a lock nut. With this arrangement, the adverse effect of the weight of the coupling means on the effective mass of the whole pickup arm device may be minimized to some extent. That is, when the head shell is formed integral with the arm main body, the coupling means between them may be eliminated, whereby the pickup arm device may be made light in weight and fabricated at less cost. Furthermore, a desired arm may be selected and mounted. For instance, instead of an arm made of a aluminum alloy, an arm made of carbon fibers may be used so as to attain desired effects. Thus the pickup arm device may be upgraded. However, this arrangement has a disadvantage in that the coupling means between the arm main body and the rotary mount is loosened, resulting in resonance of the arm main body which adversely affects the reproduction characteristics.
One remedy to the above problems is to securely connect the arm main body to the rotary mount, thereby eliminating the coupling means. Then only the replacement of a cartridge is permitted. The arm and the head shell cannot be replaced so that quality of reproduction cannot be varied as desired. Furthermore the replacement of the pickup arm becomes very difficult. That is, the lead wires from the cartridge must be removed and then the whole pickup arm device must be removed from the cabinet. In case of an automatic record player, an automatic mechanism is coupled to the rotary shaft of the pickup arm device so that the replacement of the latter is almost impossible.